Transcript Chapter 26
Chapter 26 The Atmosphere, Energy in Processes, Insolation, Specific Heat, & Isotherms BFRB Topic 5 & Topic 6 Meteorology • The study of weather • Weather is the condition of the atmosphere at any given time or place • Much of weather forecasting and prediction can be accomplished by direct observation – LOOK OUT THE WINDOW!! • To predict weather, you must make observations of the clouds, wind, temperature, humidity, air pressure and precipitation Atmospheric Composition • The Earth’s atmosphere is made up of many gases, but it is mostly nitrogen and oxygen (ESRT’s Page 11 top) • It also contains water vapor, dust, and ozone – O3 (a form of oxygen which absorbs UVC rays from the sun) • As you go higher in the atmosphere, the amount of air and air pressure (weight of air) decreases Structure of the Atmosphere • Made up of four layers, each with different characteristics (ESRT’s Page 14 top) • Troposphere- lowest layer (we live in this layer). All of Earth’s weather occurs in the troposphere. Temperature decreases as you go higher. • Stratosphere- above the troposphere, has strong winds. Temperature increases as you go higher because of the absorption of UV rays by ozone. • Mesosphere- above the stratosphere. Temperature decreases as you go higher. • Thermosphere- above the mesosphere. Temperature increases as you go higher due to oxygen and nitrogen absorbing solar energy ESRT’s Page 14 top Movement of Heat – 3 Ways • 1) Conduction- the movement of heat from molecule to molecule through contact with each other or other objects – Ex. Touching a hot pot on the stove Movement of Heat – 3 Ways • 2) Radiation- the movement of Electromagnetic Energy (heat waves) across a distance – Ex. Warming your hands in front of a fireplace • Earth receives EM energy radiated from the sun are relatively short wavelengths, and Earth reradiates this heat energy at longer wavelengths known as Infrared waves (heat) • Energy received on Earth from the sun is called Insolation (incoming solar radiation) Movement of Heat – 3 Ways • 3) Convection- the movement of heat in currents • The most effective form of heat transfer in liquids and gases – Air gets heated and expands – the molecules move apart - makes it less dense and lighter…it rises! – Colder air – molecules come together - is more dense and heavier so it sinks – It gets heated it rises, it cools it sinks – Just like in the putty-like asthenosphere!!!!! CONVECTION CURRENT DUE TO DENSITY DIFFERENCES!!!!!!!!! Greenhouse Effect • Certain gases in the atmosphere (water vapor, carbon dioxide, methane, etc.) allow short wavelengths of energy from the sun to enter the atmosphere • Earth absorbs them and reradiates the heat as infrared (heat) waves, which have longer wavelengths • The infrared waves cannot pass back through these gases and escape into space, so they become trapped in the atmosphere • This causes the temperature on Earth to increase. • This is the cause of Global Warming. Temperature Changes on Earth • Temperature changes with seasonal change occur because the sun’s insolation strikes Earth at different angles (and therefore different intensities) • Where the sun’s rays strike Earth at 90°, the insolation is concentrated in a smaller area. This causes temperatures to be the greatest. • Where the sun’s rays hit Earth at very low angles, the insolation is spread out over a large area. This causes temperatures to be low. in NYS Warmest and Coldest Months • Northern Hemisphere– Maximum sunlight is June 21st, but maximum temperature is in July – there is a lag!!! – Minimum sunlight is December 21st, but minimum temperatures are experienced in January – there is a lag!!! • It takes time for the heat to build up, and for maximum temperatures to be reached • Also, it takes time for heat to dissipate, and for minimum temperatures to be reached Warmest and Coldest Time of Day • The coldest hour is usually just before sunrise, since the Earth has been cooling off all night – there is a lag!!!! • The warmest time is later in the afternoon (after solar noon), since the Earth is still receiving more heat than it is losing – there is a lag!!! Heating Water and Land • Water and land heat up and cool off at different rates • This is due to their different heat capacities AKA SPECIFIC HEAT (P. 1 of ESRT’s) • Land needs very little energy to heat up (low heat capacity) – This allows land to heat up quickly, and also to cool down quickly • Water needs more energy to heat up (high heat capacity) – This allows water to heat up slowly and to cool off slowly – WATER IS STUBBORN!!! It takes a long time to heat up and a long time to cool down… The Rules of Absorber and Reflectors • Dark colors absorb energy well, and light colors reflect energy well (think...dark color clothes in winter, light colors clothes in summer) • Rough surfaces absorb energy well, while smooth surfaces reflect energy well (think…a mirror is smooth and reflects your image really well.) • VIF – The best ABSORBERS make the best EMITTERS of energy. • This is why radiators (heaters) are often black in color!!! How Does Water’s High Specific Heat Affect Weather & Climate? • Air temperature and other weather conditions of different locations are affected by how near or far they are from water (oceans) due to heat capacity • VIF - Water has a mitigating effect to extremes of temperature and climate • For example, a coastal city may have a average annual high of 75° and an average annual low of 40°. (35° range) • An inland city may have an average annual high of 82° and an average annual low of 33°. (49° range) • The coastal city is near the water, so the water’s temperature doesn’t change as quickly as the land’s temperature due to water’s high specific heat. ISOTHERMS • Temperatures are shown on maps by using Isotherms • These are lines which connect areas of equal temperature • These are very similar to contour lines, and they are read the same way!! • Example – closely spaced isotherms mean a fast change in temperature the same way closely spaced contour lines mean a fast change in elevation. Where in the US is the steepest temperature gradient? Where is the gentlest temperature gradient?